This invention relates to a fuel injection system for an internal combustion engine and deals more particularly with such a system wherein fuel for each cylinder or other combustion zone is continuously injected into the induction air stream for that cylinder or zone for mixing of the fuel with the air prior to and during the entry of the air into the cylinder or other combustion zone. Continuous flow injection systems of the general type with which this invention are concerned are shown, for example, by U.S. Pat. Nos. Re. 25,672 and Re. 25,701.
The general aim of this invention is to provide a continuous flow fuel injection system improved in comparison to those available or proposed in the past.
A more particular object of the invention is to provide a continuous flow fuel injection system made up of a number of units of straight-forward, reliable construction providing a long maintenance-free service life for the system.
A further object is to provide a system of the foregoing character wherein fuel injection for each combustion zone is provided by a metering unit individually associated with that zone and wherein fuel to be injected is supplied to that metering unit at a constant pressure with the metering unit including a metering valve positioned by a control pressure the value of which represents engine requirements, the rate of fuel injection from the metering unit therefore being entirely dependent on the position of its valve element.
Further objects of the invention are to provide a system of the foregoing character which may be designed to retain system pressure for a considerable time after stopping the engine so as to avoid vapor lock and which system includes no atmospheric vents thereby avoiding evaporative emissions both during engine running and shut down.